


A Little Experiment

by hb129310



Category: Gravity Falls
Genre: Emotional Manipulation, M/M, Mystery Trio, Rape/Non-con Elements, Shapeshifting
Language: English
Status: In-Progress
Published: 2015-12-13
Updated: 2015-12-13
Packaged: 2018-05-06 13:52:53
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,366
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5419499
Author URL: https://archiveofourown.org/users/hb129310/pseuds/hb129310
Summary: <blockquote class="userstuff">
              <p>After the Shapeshifter escapes containment, it’s up to the Mystery Trio to go after it before it reaches the surface. But when Fiddleford has it cornered, the creature proposes a deal of sorts. In allowing the Shapeshifter to escape, it will give Fiddleford something he has always yearned for: Stanford Pines’ love. And really, if he can’t have the real thing, why not try out an experiment to see if the other man’s form is enough?</p>
            </blockquote>





	A Little Experiment

**Author's Note:**

> So, fun fact, I wrote this months ago, back before "A Tale of Two Stans" had first aired, and we were still believing in the Mystery Trio!AU. The only thing I did change was the twin's names after the fact, just for consistency's sake. So, keeping that in mind, I guess it could count now as actual AU, but I'm okay with that. I'm not finished, so there will be a Chapter Two, eventually. I hit a writers block for a little bit, so I do plan on finishing it, but it might be a while. 
> 
> Still, I thought I would post it, and see what everyone thinks! There is a little bit of a non-con element to it, so if you don't enjoy those kind of fics, wouldn't recommend reading. Other than that, hope you enjoy reading!

"Swear to God nerd, if you don't pick up the pace, I'll feed ya to that freak of nature myself!" Stanley's threats echoed off the walls of the cave, as the three men raced through them. His twin was trailing a little behind, but because of the situation, Fiddleford couldn't really blame the taller of the two. And the engineer couldn't help but also feel a little responsible (okay, fully responsible), for this whole mess in the first place. The Shapeshifter had been growing more and more intelligent by the day, and it was only going to be a matter of time before it wanted to escape the bunker they were keeping it in. Fiddleford just hated the fact that he was the one who had been manipulated into letting the creature escape. He should've known better than to believe #210 just wanted some air. That would be the last time he would show mercy to the monster.

But he didn't have long to ponder that thought, as Stanley whirled around to face the two researchers, glaring when Stanford finally caught up, a bit out of breath. The shorter twin sighed, running a hand through his light brown hair. "Give me a break Lee," he huffed, "not everybody gets up to jog at four in the morning." The taller twin mumbled something under his breath, before turning back around to face the caves in front of them. There were two openings available, meaning there were two ways they creature could've gone. After a moment, and letting Stanford catch his breath, Stanley turned back to them. 

"Look, the way I see it, we can cover more ground if we split up. That way, no matter which way we go, one of us'll catch the son of a bitch." He turned to each of them in turn. "Fidds, you're with me on the left. Nerd, go to the right." Stanford nodded, but the scientist had a different thought in mind. 

"No. You fellas go right. I'll go on my own to the left." It was his fault #210 escaped. He needed to face the thing on his own, and, if need be, be the one to take it out. But of course, hearing this, both Pines twins exchanged pensive glances. Stanford turned to shuffling his feet, while Stanley scratched the back of his head anxiously. 

"Eh, no offense Fidds, but by yourself, I think you'd be Shapeshifter chow." Not hearing any response from Stanford, Fiddleford could only assume he shared his twin's sentiment. And the scientist was expecting that, so he had a perfectly sound explanation ready. 

"Exactly", he responded. "I can be bait. So, when, or if, I catch 'em, you fellas'll be hear me yell fer help, and know I've got 'em!" 

"Or," Stanford corrected, a bit of annoyance creeping into his tone, "you could get caught before you even have time to scream! Come on Fidds, don't be stupid! Let's just-."

"Nerd!” The two turned towards Stanley. "He's got a point." And before his twin had a chance to question it, he started up again. "Look, I know Fidds isn't exactly a heavy weight champ. But he is like a super genius, right? So I figure he can somehow outsmart the thing into doing itself in." Still seeing Ford’s doubt flash across his face, Stanley grinned placing a hand on his shoulder. "Plus, if it's up against the two of us together, it don't stand a snowball's chance in-."

"Ok, ok, I get it," Stanford admitted, a bit of a grudging smile creeping onto his face. But that vanished quickly when he turned to Fiddleford, uncertainty still lingering. "You sure about this? I still haven't cataloged all his powers, he could still have something up his sleeve that we don't know about yet." 

The engineer nodded, appearing more confident than he actually was, before smiling at his friend. "Trust me, if it does, I'll be sure to let you fellas know when you catch up to me." His smile though, quickly turned to a frown, determination setting in, weather it was from trying to show off for the two, he couldn't say. "I ain't lettin' that multi-faced slimeball trick me again."

So, with that, not having any more time to waste, as Stanley pointed out, the trio went their separate ways. Fiddleford watched the Pines twins take off to the right. And with a nervous gulp, flashlight in hand, and two way radio strapped to his belt, he raced off to the left.

Darkness was the only thing the engineer could see for a while, the cold, damp cave eerily quiet. The only sound seemed to be resonating from the droplets of water coming from the stalagmites above, and the sound of his own footsteps. "Ah, why did I have ta' go and volunteer to go alone?! I shoulda known I couldn'ta handled this!" In truth, the only reason he was even in this mess was because he had wanted to prove himself as a valued member of the trio. He wanted to prove that he was more than just the brains. Sure Stanley called his twin the nerd of the group, but even Stanford had more attributes than his smarts. He could hold his own in a fight, Fiddleford had watched him do it. But the most he was able to do was shout advice from the sidelines while taking notes for his friend in his journal. Sure they all joked about it from time to time, but in the back of his mind, the engineer couldn't help but wonder what the Pines twins really thought of him, what Stanford thought. 

He carried on, clutching the flashlight tighter than was probably necessary, when he heard it. A scuttling across the cave floors, just up ahead. Feeling the blood in his veins turn to ice, he paused in hunting for his radio, and turned his flashlight towards the noise. And sure enough, there behind an upcoming corner was the Shapeshifter's silhouette. Its menacing backdrop was there for a split second more, before disappearing, the scuttling continuing as it resumed movement. Fiddleford gasped silently, and he was ashamed that he took his first instinct of hiding behind a nearby rock formation, clutching his flashlight in fear. He sat there for another moment, in the cold, dark cave, panic starting to set in. But after a moment, he could still hear the creature's scuttling, which was strange. The engineer paused in as he craned his head to get a better listen. 

Sure enough, it didn't sound as if #210 was moving any farther down the cave. Fiddleford gasped as a thought suddenly flashed through his mind. Could it be...trapped? Was that a dead end? It had to have been, or the creature wouldn't have bothered to stick around. This could be his only opportunity to corner it, and if he missed it.... The engineer shuddered at the thought of #210 reaching the surface. Who knows what kind of havoc it could wreak in the world above? There were innocent people who could get hurt...And at the moment, he was the only one who could do anything about it. 

Resolve flooded through his body, as, heart racing, he tore out of the hiding place, and around the corner to face the Shapeshifter, once and for all. He made sure make sure his radio was easily accessible, to let Ford and Lee know that he had found it, just for good measure. Flashlight at the ready, he shined it upon the corner just as he rounded it, fully prepared to catch the monster. 

But all that confidence vanished instantly, as, instead of seeing #210's massive alien form, there was ....nothing? Fiddleford gasped, almost dropping his flashlight. It was a dead end, there was no doubt about that, but there was nothing there....No, he couldn't have been wrong! There was no way that the scuttling noise had been anything other than....

"Looking for something Fiddleford?" Ice once again washed over his bloodstream, and froze him to the spot. Terror level skyrocketing, he turned around to face none other than Experiment #210. He was only slightly relieved to see that the creature had decided to take the form of that ridiculous baked beans mascot instead of its natural one. Sparing a quick glance at his was functional, the engineer glared at #210, despite the fear ever present in the back of his mind.

"You," he spat, feeling nothing but hate for the creature. The Shapeshifter however, didn't appear intimidated in the slightest. In fact it had its arms crossed, a haughty smile in place. 

"Me," it quipped back, an expectant eyebrow raised, as if expecting McGucket to come at it brandishing the flashlight. And, in truth, Fiddleford probably looked a bit ridiculous, as his only defense was a flashlight and a radio. Still, he couldn’t let #210 know that he was scared out of his wits. So, heated glare in place, he held the instrument almost protectively in front of him, while his other hand started gravitating to the radio strapped to his belt.

“N-not a step closer, ya’ hear?!” The waver in his voice couldn’t be helped, but at least if he turned on the device, Stanford would be able to-.

“Oh, come now Professor,” a calming purr emanated from the creature. “I’m sure there’s no need for such drastic measures.” In a seeming show of good faith, #210 held up its hands in surrender, which may or may not have caused Fiddleford to start, flashlight getting a bit shakier in his grasp. Once he registered the message however, he couldn’t help but scoff.

“Oh, yes, forgive me for acting irrational. You only attacked me and almost left me to die in that cryogenic tube!” The engineer let out a bitter chuckle. “Nah, clearly I’m the one who need to calm down!” This was why he never trusted #210 in the first place. Shapeshifting on its own seemed an untrustworthy ability, but the creature’s taste for talking cemented his worries. Fiddleford had seen the way it liked to twist the trio’s words, manipulating them to get more information about the world above. Well, it wasn’t going to work anymore. 

However, when #210 went to move, instead of an attack, the shifter sighed, in what could just about pass for regret, if Fiddleford didn’t know any better. “Yes, about that….” It ran a hand through its borrowed grey locks, looking up to the ceiling of the cave. “I am truly sorry you know. It’s just….Well, being a creature that was born never seeing sunlight, one can tend to get a bit stir crazy.” Pausing briefly, it saw Mcgucket’s silence as permission to continue. “Even with all the wonderful knowledge you and your friends have bestowed onto me, I suppose nothing could replace a first-hand experience of the Earth.”

Fiddleford, during this little speech, couldn’t help but soften his glare a bit. But that didn’t change the facts, and he continued to level the creature coldly. 

“Still. No reason for ya’ to go and attack me. You know what you were doing. Ya’ couldn’t’ve been that desperate.” Though maybe it was, all things considered. The trio had been a little restrictive on where it could and couldn’t go. Didn’t change the fact that #210 was an untrustworthy monster, but it did put things a bit into perspective. 

The shifter must have been wise to his thoughts, because it levelled the engineer with a somewhat deadpan expression, one eyebrow lifted. “Now Professor, be honest with me. Did any of you trust me that much? Would you really have let me venture out, not suspicious at all of my intentions?” Fiddleford’s gaze wavered, giving the creature all the conformation it needed. With a haughty sneer, it turned away. “That’s what I thought. I know you and Stanford would have been polite in your rejection if I asked, but that hulking ape of a twin he has would have suggested dissecting me on the cave floor. You can perhaps see why I had no other choice.”

Fiddleford couldn’t help but silently agree with this. The taller of the Pines brothers wanted to be rid of the creature since Day 1, and would try to find any excuse to do so.

#210 paused yet again, hearing no retort from the bespectacled man. After a moment of staring each other down, the creature’s sneer morphed into a resigned frown. “I suppose, though, there’s no need to lament on what could have been. It appears you’ve caught me. No doubt you’re going to report my location to the others….”

Fiddleford snapped out of his thoughts, seemingly remembering the whole reason he’d wanted to split up in the first place. He glared in determination, standing up a bit straighter, puffing out his chest. “That’s right! Soon as I push this button, they’ll be here in seconds!” And with that, not having anything more to say, the professor’s finger started gravitating towards the call button on the radio….

“Oh yes, and won’t they be proud.” The purring lilt of #210’s voice stopped him. Fiddleford looked back at it, and the remorseful frown was now replaced with a sly grin. “Their delicate little poindexter, all grown up and hunting monsters all by himself….” Without warning, the shifter began practically strolling towards Fiddleford. All thoughts of calling for the twins flew from his mind as he instinctively started backing away. “Why, they’ll be practically over the moon.” Its sly grin turned shark-like. “Especially Stanford….”

Fiddleford’s blood ran cold at the obvious double meaning in the shifter’s words. He paled, all the while #210 crept ever closer. The engineer, backed up further and further with each step, before he ran into something from behind. He realized with horror that the creature had literally backed him into a corner, with little to no escape. And worst of all, was that lingering implication in the last sentence it had uttered. 

After a moment, of what felt like an eternity, all the engineer could do was sputter like a gasping fish. Finally, he turned to try and look #210 in the eyes, a few beads of sweat rolling down the side of his face. “W-what?” It couldn’t know….no, it was just being the manipulative slimeball it had always been….But why had it used that tone?! Why-?

Fiddleford’s erratic train of thought was swiftly interrupted by a low, sinister chuckle coming from the shifter. The creature was now almost towering over the man, mere feet away. “Ah yes….,” it crooned, “I can just picture it….” A faux wistful look was in its eyes. Without warning, #210 leaned even closer, practically whispering. “He and that oaf will come running to their poor little nerd’s rescue, only to find the monster vanquished, and the day saved…..” Another light chuckle. “Why, Stanford will be so grateful he may practically throw himself into your arms….”

The lanky man’s eyes went impossibly wide. There was no doubt now that the shifter was implying exactly what Fiddleford thought it was. And that terrified him.  
Meanwhile #210 had noticed the reaction, and instead of stopping, it just kept speaking in that same honeyed tone, an almost gentle smile on its face. “Wouldn’t that be nice Fiddleford,” it questioned. 

“To finally have that which you’ve craved for so long….Stanford’s love?”

The engineer couldn’t respond for at least a few seconds, as utter horror was starting to sink in with each word. #210 knew?! How had it, when Fiddleford himself had made sure to keep it hidden as much as possible? At first, when the twins had come to Gravity Falls, the engineer had merely seen Stanford as an intellectual equal. But overtime, and after a few close calls with the supernatural, it was clear to him that he would do anything to spend time with the researcher. Only in the deepest reaches of his mind, however, did Fiddleford even dare call the emotion he felt for the other man love. 

And he wanted to keep it that way, in fear of rejection, heartbreak, or worse.

The lanky man eventually grasped for a few coherent words, a slight tremor in his voice. “I-I don’t-…” The stutter started off small, unsure and confused. But it swiftly morphed into anger. He was once again glaring daggers at #210, trying to regain control of the situation. “No,” he finally exclaimed, volume building as he continued. “No, get off me!” 

And it was here that McGucket actually physically shoved the creature back several feet. The latter must have been just surprised as he was, because it made no move to do anything, even when Fiddleford threw it a threatening glare. “I don’t know what in the Sam Hill you’re talking about,” the scientist insisted. Really, that’s all he could do in this situation, denying it to the best of his abilities. 

“You’re not playin’ your mind games with me anymore you slimeball!”

But before the lanky man could even think about reaching for the radio again, #210 had found its voice. And it seemed to recover from the shock of Fiddleford’s outburst, because now it was back to wearing a grin. “Now, now,” it tried, “let’s not be too hasty….” Before the scientist could move even an inch from where he had been before, the shifter was back to pitting him against the wall, perhaps even closer than before. It lifted one of its eyebrows, grin still in place. “What say I offer assistance to your little problem?”

Fiddleford glared at it for a moment more, before forcing his way past #210, turning his back on it. Time to end this. “Not listenin’,” he responded pointedly, and with that, grabbed the radio, centimeters from alerting his friends. Once the twins came, everything would be all right, they would freeze #210, and he could forget this whole th-.

“Oh come on Professor. Be a little more open minded…..”

The familiar voice caused Fiddleford’s radio to fall out of his hands, crashing to the cave floor. The engineer, without thinking, whirled back around to face the Shapeshifter. But unfortunately, his suspicion was confirmed when he saw, instead of the creature, an exact replica of Stanford Pines. 

Smiling amicably, one eyebrow raised, the brown eyes locked straight onto Fiddleford. “I’m not asking for much,” it cooed in the researcher’s voice. Before the engineer had time to think, he was back to being cornered, one of #210’s arms stretched out onto the cave wall behind him. “How about we test something, hm?” 

Fiddleford’s eyes clamped shut at the damn near perfect impression of his friend, trying with all his might to block it out. “Stop it.”

This only seemed to give the Shifter more ammunition, seeing as how it got a reaction. The lanky man didn’t have to look up to see the smirk on #210’s face. “Oh, come on Fiddleford,” it continued, voice practically dripping with false sweetness, “Why not hear me out, huh?” A gasp escaped him as he felt the creature trace its borrowed hands along his shoulders in a surprisingly gentle way. “How about, you let me get outta here….,” it whispered, as Fiddleford winced, the sudden tactic the creature was using becoming more and more effective than he cared to admit.

Before he could think anymore on that though, #210 gently cupped the engineer’s chin, tilting it up with little to no resistance. Having no choice but to open his eyes, Fiddleford gazed upon the creature’s face, a perfect, yet imperfect copy of his best friend. The sinister flash in its brown eyes was merely an afterthought, as Fiddleford’s head was swimming with a torrent of conflicting emotions. 

The Shifter seemed to sense his little trick was working, as its gentle smile turned into a positively sinful smirk. “And in return,” it continued, in an equally deviant tone of voice, “we....” In a single movement, it had leaned in, arms now planted firmly on either one of the engineer’s shoulders, coming so close to Fiddleford that the taller man could feel it’s breath on his neck. “We can conduct a little experiment…”

**Author's Note:**

> So, that was Chapter 1. Again, I do plan on continuing this fic, but it won't be for a while. Still, hope it's interesting for everyone so far!


End file.
